Geological characteristics and development strategies for Cambrian Longwangmiao Formation gas reservoir in Anyue gas field, Sichuan Basin, SW China

Abstract Seismic, drilling, logging and production performance data were analyzed to study the key geological factors such as reservoir properties and gas/water distribution, which influence the development of the Lower Cambrian Longwangmiao reservoirs in the Moxi block, Anyue gas field, Sichuan Basin, and the development strategies are established. The results indicate that: (1) Four stages of grain shoals developed longitudinally and two main shoals with one trench formed laterally in the development area; (2) Three types of reservoirs are identified, which are reservoir with millimeter sized dissolved vugs, reservoir with solution pores, and reservoir with inter-particle/inter-crystal pores; (3) Low matrix porosity but mid-to-high permeability affected by developed high-dip fractures; and (4) Three gas/water contacts (GWC) can be defined and step down from west to east, with a unique gas/water contact of −4 385 m in the target developing area. Based on geologic characterization, reservoir simulation and case study of similar gas reservoirs, the development strategies are made: to select the main grain shoal area as the prior production area; to locate wells on the structural high to delay edge water breakthrough and prolong stable production; to drill horizontal wells enhancing single well deliverability; to keep reasonable production of wells for improving the production effect.